P06D2

Code

Generic P — Powertrain

Sensor Reference Voltage E Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 46 RU: 25

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Page language: EN

Causes

Open or damaged wiring harness between ECM and sensor(s) on reference circuit E
Corroded, loose, or pushed-out connector pins at sensor or ECM connector
Failed sensor(s) drawing the reference circuit out of range
Short to ground or short to battery on the reference wire
Faulty ECM (internal reference voltage driver failed)
Aftermarket accessories or repairs that disturbed wiring or pins

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Stored P06D2 freeze-frame/diagnostic data
Faulty or erratic sensor readings for devices on reference E
Possible reduced engine performance or limp mode if sensor data lost
Intermittent faults that may change with vibration or connector manipulation

What to check

Retrieve freeze frame and pending codes; identify which sensor(s) share reference circuit E
Visual inspection of wiring and connectors for damage, corrosion, or loose pins
Backprobe sensor connector and measure reference voltage with ignition ON (engine OFF)
Measure voltage at ECM reference pin to confirm presence/absence of reference
Check continuity between sensor reference pin and ECM reference pin
Inspect for shorts to ground or to battery on the reference wire

Signal parameters

Nominal reference voltage: approximately 5.0 V (typical ECU sensor reference)
Acceptable range: usually ~4.75–5.25 V (check manufacturer spec)
Open circuit: ~0 V at sensor connector
Short to battery: ~12 V present on reference wire
Measurements: Key ON, Engine OFF; use DMM; backprobe connector; avoid powering sensor loads while testing continuity

Diagnostic algorithm

Confirm code and collect freeze-frame/live data to identify affected sensor(s) on reference E.
Perform a careful visual inspection of wiring harnesses, clips, and connectors for damage, pin push-out, corrosion, or signs of repair.
With ignition ON (engine OFF), backprobe the sensor reference pin and measure voltage. If ~5 V present at ECM but not at sensor, suspect open/poor continuity.
Measure voltage at the ECM reference terminal. If voltage absent at ECM, suspect ECM internal fault or related power/ground/fuse.
Check continuity between sensor reference pin and ECM reference pin with IGN OFF. Open indicates broken wire; low resistance should be present (near 0 Ω).
Check for short to ground or battery by measuring resistance from reference pin to ground and to battery + with IGN OFF. Very low to battery indicates short to power; low to ground indicates short to ground.
Wiggle connectors and harness while monitoring voltage or live data to find intermittent faults. Repair/replace damaged wiring or connectors.
If wiring and connectors test good and sensor still causes the fault, disconnect the sensor and see if code clears or changes; test/replace suspect sensor(s).
If fault persists with known-good sensors and good wiring, verify ECM power, ground, and fuses. If all are good, consider ECM as the remaining cause and follow manufacturer procedures for ECM testing/replacement.
After repairs, clear codes and perform a drive cycle to confirm the issue is resolved and code does not return.

Likely causes

Open/blown reference wire between sensor and ECM
Poor connector contact or corrosion at sensor or ECM connector
Sensor shorting internal reference to ground
ECM reference driver failed (less common)

Fault status

⚠️ Status

Sensor Reference Voltage E Circuit/Open — The engine control module detects an open or incorrect reference voltage on sensor reference circuit E (missing/low/high voltage or open circuit).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours